This invention relates generally to methods and apparatus providing advanced operating features for audio and/or video programs recorded on disk media, for example recordable digital video disks.
Various devices have been developed to enable consumers to record video and audio programs for later presentation. Such devices include tape recorders, video cassette recorders, recordable compact disks, and most recently, recordable digital video disks (DVD). A DVD that can be recorded on only once, and thereafter is essentially a DVD read only memory, is referred to by the acronym DVD-R. The acronym DVD-R is also used generally to refer to the write-once, or record-once, technology. Several formats are available for DVD""s to be recorded on, erased and re-recorded, that is overwritten or rewritten. These are referred to by the acronyms DVD-RAM, DVD-RW and DVD+RW. As of this time no uniform industry standard has been adopted. The acronyms DVD-RAM, DVD-RW and DVD+RW are also used generally to refer to the respective rewritable technology. Reference herein to rewritable DVD technology, devices and methods is generally intended to encompass all of the standards which are now being used, as well as those which may be developed in the future.
In many cases, the program presentations are recorded in the viewer and/or listener""s absence, for presentation at a later, more convenient time. This is referred to as time shifting the program. At other times, a program is being viewed and/or listened to without being recorded, and with out any interest in a recording, but the viewer""s and/or listener""s attention is interrupted, for example by a telephone call or an unexpected visitor. If the viewer and/or listener is watching a television program, for example, and has a cassette tape in a VCR, or can retrieve and load such a cassette tape quickly, the program can be recorded. However, the viewer and/or listener cannot view and/or listen to the program in its entirety, and in a proper time sequence, until after the recording has been completed. The time to completion of the recording can be short or long, depending on the length of the program.
A desirable feature in a DVD device would enable a viewer and/or listener to initiate resumption of the program presentation as soon as the interruption or pause has ended, without sacrificing the program content during the interruption or pause.
Although rewritable DVD technology is generally available, operation is limited to such basic functions as play, record, fast forward reverse and stop. Pause is available, but only as a counterpart to pause operation in a VCR, for example interrupting the play back of a prerecorded program or interrupting the recording of a viewed program to eliminate commercials from the recording. Unlike computer hard drives, recordable DVD devices have a very significant additional function, which is playing back prerecorded DVD""s. Thus, there is an economic incentive to develop rewritable DVD technology, including methods and devices, that can be used instead of a computer hard drive. It is a challenge to provide such devices with improved, advantageous features without compromising the goal of decreasing costs and increasing sales. Such novel DVD features should include the ability to simultaneously view and record on a disk medium in a seamless fashion, without the high operating speed of a computer hard drive. A recordable DVD device with a single head for reading and writing cannot read and write simultaneously. Accordingly, the terms seamless and simultaneous are used herein to denote that recording and playing back program material in accordance with the inventive arrangements has the appearance of being simultaneous to the viewer and/or listener, even though the functionality is actually alternating or multiplexed.
Another issue relates to the number of times program material can be recorded and re-recorded on disk media, particularly the same DVD. Repeated recording in the same section of the disk will exhaust the lifetime of the disk prematurely. It is desirable when implementing novel features, particularly features that can require large amounts of overwriting, to prevent repeated recording in the same sections of a rewritable DVD to prevent premature exhaustion.
Another issue relates to the maximum data rates of minimally capable rewritable DVD devices. A basic rewritable DVD device, having for example a 1X (one times) read and a 1X (one times) write capability, typically has maximum data rates for recording or playing back of approximately 11 megabits/second. Accordingly, it is desirable to implement novel features that can be implemented within the constraints of the maximum available data rates.
A method in accordance with the inventive arrangements for writing and rewriting onto a disk medium capable of being rewritten only a limited number of times, comprises the steps of: encoding as data blocks all programs to be recorded; writing at least a portion of any encoded program onto a track on the disk medium as a given sequence of the encoded data blocks; and, when overwriting the given sequence of encoded data blocks with a subsequent sequence of encoded data blocks, not overwriting the beginning of the given sequence, whereby said overwriting precesses along said track.
Another method in accordance with the inventive arrangements for writing and rewriting onto a disk medium capable of being rewritten only a limited number of times, comprising the steps of: encoding as data blocks all programs to be recorded; writing at least a portion of any encoded program onto a track on said disk medium as a given sequence of said encoded data blocks; and, precessing along said track when overwriting said given sequence of encoded data blocks with a subsequent sequence of encoded data blocks.
An apparatus in accordance with the inventive arrangements for writing and rewriting onto a disk medium capable of being rewritten only a limited number of times, the apparatus comprising: a first signal processor for encoding as data blocks all programs to be recorded; a pickup assembly for writing data onto the disk medium and reading data from the disk medium; a servo system for the pickup assembly; a second signal processor for decoding the encoded data blocks; a controller operable with the pickup assembly and the servo system for enabling at least a portion of any encoded program to be written onto a track on the disk medium as a given sequence of the encoded data blocks; and, the controller, when overwriting the given sequence of encoded data blocks with a subsequent sequence of encoded data blocks, precessing along the track.
Certain new features for rewritable disk media players, for example rewritable DVD devices, will involve substantial amounts of rewriting over previously recorded data. One example is the record during pause and playback feature described herein. Another example is protracted use of the same DVD for recording programs, particularly if every new recording is programmed to begin at the beginning of the track. In accordance with the inventive arrangements the useful re-recording lifetime of a rewritable DVD can be maximized by precessing the beginning of overwriting blocks of encoded data along the track.